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Interrupt Handling

Interrupt handling is very different with the NewWorld approach. The interrupt code has been rewritten to allow for dynamic creation of the interrupt layout. The new code has two features that did not exist in the old code. One is that interrupt latency has been reduced to such an extent as to make it negligible. The other is that the interrupt handling code no longer requires changes to support a new machine unless it has new interrupt controller hardware. The description of the interrupt layout is now part of an Open Firmware interrupt tree that is interlaced within the Open Firmware device tree. The Trampoline code uses this interrupt tree to build the Mac OS native interrupt tree.